This invention relates to a polyfunctional liquid urethane-containing composition. More specifically this invention relates to a composition comprising an adduct which contains a plurality of internal urethane linkages, has isocyanate functionality, and additional, different, functional group(s) that under normal conditions are not susceptible to entering into reaction with isocyanate functionality.
In general, urethane-containing adducts are prepared by reacting an organic polyisocyanate with an active hydrogen-containing substance. The reaction may be conducted in the presence of a solvent and various addition sequences of isocyanate with active hydrogen-containing substances employed so as to arrive at an end product that can be substantially free of any isocyanate functionality or isocyanate-reactive functionality such as disclosed in U.S. Pat. No. 4,079,028. The products disclosed are essentially non-reactive products having value as a rheology modifying agent in various application areas including paint compositions and cosmetics. However it is noted that the procedure of preparing adducts as reported in U.S. Pat. No. 4,079,028 is deficient with respect to control of molecular weight build-up leading to undesirable gelation or solids formation. Liquid adducts are generally favored for convenience of industrial processes.
There is now a desire to modify such adducts and provide alternative molecules that are "tailored" to perform multiple tasks whereby their rheological characteristics can be exploited in other application areas, including surface protection and adhesives. By surface protection, it is understood the protection of a surface by coating that surface with a protective substance. By adhesive, it is understood the bonding of a first surface to a second surface that can be of a like or different substrate. In conventional surface coating chemistry and adhesion technology, frequently many different molecules are used in sequence or in combination to achieve the desired end result. Accordingly, it would be attractive to provide an alternative molecule which can reduce, or even overcome, the need to use multiple molecules.
The present investigation has been directed to overcoming the process deficiencies associated with U.S. Pat. No. 4,079,028 and at the same time to providing a "tailored" reactive molecule having value in surface coating and adhesive application areas. From our investigations, it is now found that such adducts can be prepared via a solvent free process with careful control of the reactants, presence of processing aids, and process conditions. By the term "processing aids", it is meant substances which act as catalyst to reactions involving the isocyanate functionality and especially substances which promote the formation of the urethane linkage.